Vehicles typically include seat belts to help restrain occupants in the event of a sudden stop or accident. In some vehicles the seat belts are anchored to the frame independently of the seat such that forces exerted upon the belt by an occupant are transferred directly to the frame. In such configurations the seat can be relatively light-weight, since the seat is not required to function as an occupant restraint. Unfortunately, these designs can be impractical for use with adjustable seats, which can be moved forward and backward and reclined, as the seat belts must be likewise adjustable for the various seating positions while retaining their intended safety features. Seats with separately anchored restraint systems are also more difficult to incorporate into the cabins of a wide variety of vehicle types, as the floor and wall structures of the vehicle may not readily accommodate the necessary frame anchor points for lap and shoulder belts.
To overcome the aforementioned limitations of separately anchored seat belts vehicle designers are increasingly turning to configurations wherein the seat belts are integrated with the vehicle seats. In such configurations the seat belts are anchored to the seat frame which is in turn anchored to the vehicle frame. Accordingly, the seat belts can be located more optimally to accommodate variations in seat position and orientation. These configurations also have an advantage in that the seat assembly, together with the seat belt, can be installed as a single unit in the passenger compartment at the time of vehicle manufacture.
One important consideration when the safety restraint belt is integrated with the seat assembly is that the seat assembly must be designed to allow unrestricted movement of the seat belt webbing as it is extended and retracted so that the inertia reel retractor can function properly without causing discomfort to the occupants. Similarly, the seat belt webbing should be protected against abrasion or wear that could weaken the webbing. In addition, the seat assembly should protect the webbing against binding or damage caused by passengers and/or objects coming into contact with the seat belt.
Current integrated seat restraint systems often locate the seat belt retractor on the seat's frame, beneath the seat cushion, and route the seat belt webbing upwardly along a rear portion of the seat back. In these designs the portion of the path of the seat belt webbing, generally between the seat cushion and the seat back, may be exposed. Ideally this exposed region would be enclosed to protect the seat belt webbing potential restriction, wear and damage caused by occupants and/or objects coming into contact with it. However, enclosing the exposed region is problematic because doing so can hinder the range of motion of the seat back.
There is a need for a way to protect a vehicle seat belt web as it passes between a seat cushion and a seat back without hindering the range of motion of the seat back or impeding the operation of the seat belt.